Many synthetic materials are presently used as surgical sutures. These materials may be used as single filament strands, i.e., monofilament sutures, or as multifilament strands in a braided, twisted or other type of multifilament construction. Synthetic sutures have been made from materials such as polypropylene, nylon, polyamide, polyethylene, polyester such as polyethylene terephthalate, and segmented polyether-ester block copolymers. In addition, absorbable synthetic sutures have been prepared from synthetic polymers such as polymers containing glycolide, lactide, dioxanone and/or trimethylene carbonate.
Natural materials have also been used to make sutures. For example, silk has been used to make nonabsorbable sutures. As another example, catgut sutures are absorbable sutures made from a natural material.
Sutures used for the repair of body tissues are placed in intimate contact with the tissue and, frequently, completely within the body. Thus, sutures may not contain components that are irritating to body tissue. Accordingly, any tissue-irritating components used during manufacture of the suture must be stringently removed from the suture prior to use.
For example, ethylene oxide has been used to sterilize sutures and other surgical devices. However, since ethylene oxide is an irritant to human tissue, stringent removal of any residual ethylene oxide is required before the suture packages are sealed.
As another example, xylene has been used in the processing of suture material as a solvent for suture coating materials employed to improve the handling characteristics such as knot-run-down to reduce frictional chatter and fraying. In U.S. Pat. No. 3,187,752 xylene is used as a solvent for applying polymeric silicone to a braided silk suture. In U.S. Pat. No. 4,185,637 a poly (p-dioxanone) braided suture is coated with a gelatinous dispersion of calcium stearate in xylene.
Xylene is not soluble in water and is irritating to human body tissue. Thus, if xylene is used (e.g., as a solvent) at any point in a process for making a surgical device, any residual xylene must be removed prior to use, preferably prior to packaging.
It would be desirable to provide an easy and efficient method for removing residual xylene from a suture or other surgical device.